Recently, as the form of a packaged battery, the trend is shifting from a shrink-packaged product obtained by wrapping a battery body with a heat-shrinkable film, toward a blister-packaged product obtained by forming a recess in a plastic sheet, housing a battery body in the recess and sealing the opening of the recess. In the case of the blister-packaged product, a battery that is not shrink-packaged is housed in a blister package.
Herein, as an example of battery assemblies, a schematic vertical sectional view and an exploded oblique view of an alkaline dry battery 6LR61, are shown in FIG. 11 and FIG. 12, respectively.
A unit cell group constituting the alkaline dry battery 6LR61is composed of a first unit cell row 12a (having a sealed portion facing upwardly) including three unit cells and a second unit cell row 12b (having a sealed portion facing downwardly) including three unit cells, in which these rows are connected in series.
Each unit cell is an alkaline dry battery in which the power generating elements are housed in a cylindrical steel battery case having a bottom face, and the opening of the battery case is sealed by a nylon gasket having a negative electrode current collector and a negative electrode terminal plate. The unit cell is covered by a heat-shrinkable resin tube, except for the upper and lower terminal sections thereof. The above-described unit cell group is housed in an outer jacket 24.
Disposed as an upper connecting plate at the upper portion of the unit cell group is an insulating paper 17, which has apertures respectively formed in the portions corresponding to the terminal section at the top of the unit cells, as well as having two lead pieces 19, attached on the lower side portion of these apertures, for connecting in series the unit cells of the first unit cell row 12a and the unit cells of the second unit cell row 12b. The two lead pieces 19 are spot-welded to the terminal section of the unit cells at the portions provided with the apertures of the insulating paper 17.
Disposed as a lower connecting plate at the lower portion of the unit cell group is an insulating paper 18, which has apertures respectively formed in the portions corresponding to the terminal section at the bottom of the unit cells, as well as having three lead pieces 20, attached on the upper side portion of these apertures, for connecting in series the unit cells of the first unit cell row 12a and the unit cells of the second unit cell row 12b. The three lead pieces 20 are spot-welded to the terminal section of the unit cells at the portions provided with the apertures of the insulating paper 18. A spacer 16 is disposed on the lower side of the insulating paper 18 which is the lower connecting plate.
On the lower side of the terminal plate 13 which is made of synthetic resin and provided with a positive output terminal 14 and a negative output terminal 15, an insulating paper 21, a positive electrode lead piece 22 and a negative electrode lead piece (not shown) are mounted with rivets. The output terminals are respectively connected to the lead pieces by means of rivets.
The end portion of the lead piece 22, which is connected to the positive output terminal 14 on the terminal plate 13, is connected to the positive electrode terminal (the right end in FIG. 12) of a unit cell in the second unit cell row 12b at around the apertures of the insulating paper 21. Further, the lead piece connected to the negative output terminal 15 is similarly connected to the negative electrode terminal (the left end in FIG. 12) of a unit cell in the first unit cell row 12a at around the apertures of the insulating paper 21. In this manner, six unit cells are connected in series, so that output power can be taken out from the positive output terminal 14 and the negative output terminal 15.
Further, as an example of stacked dry batteries produced by stacking plural unit cells apart from the above example, a schematic vertical sectional view of a stacked dry battery 006P is shown in FIG. 13. A stacked body produced by stacking six unit cells 35, is housed in an outer jacket 38. Each unit cell 35 comprises, for example, a connecting electrode plate 32 composed of a zinc plate and a carbon coating provided on the undersurface of the zinc plate, a paper-made dish-like separator 33 with a pasting agent applied on the surface thereof facing the connecting electrode plate 32, a molded body of a positive electrode mixture 31 and a heat-shrinkable tube 34 for covering these components.
The stacked body is covered by wax and a heat-shrinkable tube 37. Then, the heat-shrinkable tube 37 is heat-shrunk such that the rim of the upper end and the rim of the lower end of the heat-shrinkable tube 37 closely adhere to the upper periphery and the lower periphery of the stacked body, respectively.
A positive output terminal 41 disposed on a terminal plate 39 is connected to a positive electrode lead plate 42, thereby connecting the positive electrode lead plate 42 to a positive electrode current collector plate 36. Further, a negative electrode lead plate 43 is connected to the connecting electrode plate of the unit cell located at the lowermost part of the stacked body and to a negative output terminal 44 disposed on a terminal plate 39.
An assembly of multiple cells of alkaline dry batteries 6LR61, manganese dry batteries 6F22 or the like, comprises a terminal plate provided with positive and negative output terminals in close proximity to each other on the same face thereof. In such an assembly of multiple cells, since the positive and negative output terminals are in close proximity to each other, when a battery is taken out from the blister package and put, for example, in a pocket, electrical conduction may occur between the terminals by a coin, a metal chain or the like in the pocket, thereby easily causing an external short circuit. For this reason, measures are being sought for, which is able to prevent the external short circuit between the output terminals, without shrink-wrapping individual battery assemblies.
Hitherto, various methods have been devised for preventing the external short circuit and further identifying the unused state, (so-called, virginity), of an assembly of multiple cells. For example, Japanese Unexamined Utility Model Publication No. Sho 52-72029 discloses a sealing member for a positive electrode terminal surface comprising an insulating ring made of a thermoplastic synthetic resin with an L-shaped cross section, and a bridging band-like portion formed integrally with the insulating ring. However, there is a problem that this sealing member not only has a complex structure thereby making the integral molding step itself complicated, but also is relatively difficult to install on the positive electrode terminal surface. Further, this sealing member is not applicable to the negative electrode terminal surface.
Additionally, Japanese Unexamined Utility Model Publication No. Sho 54-48934, discloses an old-or-new classification plate for dry batteries obtained by providing small pores on the periphery of the center of an insulating thin plate such as paper, and applying an adhesive on a portion thereof other than the center. Further, Japanese Laid-Open Patent Publication No. Sho 58-169768 discloses a sealing tape for dry batteries obtained by applying an adhesive on one surface of a band-like tape body to cause a band-like film to adhere along the central portion of the resulting adhesive surface, and providing slits to form the above film such that the sealing tape can be partially stripped off. However, in the above cases, it is necessary to use an adhesive having the so-called adhesiveness, and the above-described sealing tapes are applicable to both the positive electrode terminal surface and the negative electrode terminal surface; however, they have a problem of poor workability in adhesion.
Moreover, each of the sealing members as described above is applied to a cylindrical battery having a positive electrode terminal and a negative electrode terminal respectively on the upper and lower portions thereof, and cannot be directly applied to an assembly of multiple cells comprising a terminal plate provided with positive and negative output terminals in close proximity on the same surface thereof.
Therefore, it is an object of the present invention to provide an assembly of multiple cells having a protective tube composed of an insulating material covering an output terminal, which does not necessitate the use of an adhesive or the processing of the protective tube into a complex shape, is capable of electrically isolating the positive output terminal and the negative output terminal by the protective tube with ease and does not require the protective tube to be removed from the assembly of multiple cells at the time of use, while also allowing an easy removal of the protective tube.